Even though I am hopeless romantic I don't believe in love at first sight. You can be attracted to a person when you first see them, but calling it love is little too far fetched for me. It of course depends on what people define as love, but to me true love cannot exist when you don't really know the person. To me love is more than a feeling of likeing someone alot. It is a sacrifice.
But I have experienced something that some would consider "love at first sight". I would word it more like "crush at first sight". I have met girls that I have found highly attractive, but I have never really knew who they were. I have had idea what they might be like and I have more felt "love" towards that idea of the girl rather than the person itself. I suppouse that feeling is very similiar to love and perhaps it is love, but only on lower level. However I still rather call this phenomenon a crush rather than love. Crushes are something you can have without making an effort, but love is something that builds over time when you can take both good and the bad from the person.